The present invention relates to a magnetic circuit structure, and to a power-generating device and an electronic device using the structure. More particularly, the present invention relates to the structure of a magnetic circuit constructed by laminated members composed of stacked magnetic materials.
Small portable electronic devices, such as electronic wristwatches, sometimes have small power-generating devices built therein, which generate electric power by being driven by kinetic energy produced by rotation or swing of an oscillating weight in response to movement of the device. FIG. 18 shows the structure of the principal part of such a small power-generating device. FIG. 18 is a general perspective view showing the general structure of a power-generating section of a power-generating device 10 built in an electronic wristwatch.
The electronic wristwatch with the power-generating device 10 built therein includes, although not shown, an oscillating weight supported rotatably on the center of rotation so as to have a biased weight distribution, and a transmission gear train connected to the oscillating weight. The transmission gear train is meshed with a gear portion 11a integrally formed with a rotatably supported rotor 11 so as to rotate the rotor 11. The rotor 11 rotates inside a rotor hole 12a formed at about the center of a stator yoke 12 which is composed of stacked magnetic layers or magnetic plates of a thin soft magnetic material in order to reduce core loss. The outer peripheral portion of the rotor 11 functions as a rotor magnetic pole, and the inner peripheral surface of the rotor hole 12a of the stator yoke 12 functions as a stator magnetic pole. Both end portions 12b of the stator yoke 12 are in contact with both end portions 13b of a magnetic core 13 so as to overlap with the lower sides thereof. In this state, the stator yoke 12 and the magnetic core 13 are fixedly joined by joint screws 14. An electromagnetic coil 15 is wound on a shaft portion 13a of the magnetic core 13. The magnetic core 13 also has a structure in which magnetic plates made of a thin soft magnetic material are stacked, in a manner similar to that of the stator yoke 12.
FIG. 19 is an enlarged general schematic sectional view showing a joint section between the stator yoke 12 and the magnetic core 13 in the above-described power-generating device 10. The stator yoke 12 and the magnetic core 13 shown in this figure are each formed of a laminate of two magnetic plates. The end portion 12b of the stator yoke 12 and the end portion 13b of the magnetic core 13 are provided, respectively, with joint holes of corresponding shapes at corresponding planar positions. A tube 16 press-fitted in a main plate 17 is passed through the joint holes, and the joint screw 14 is screwed into the tube 16. The end portion 12b of the stator yoke 12 and the end portion 13b of the magnetic core 13 are vertically clamped by a head portion 14a of the joint screw 14 and a flange portion 16a of the tube 16, and are thereby fixedly joined to each other.
Attempts have been made to reduce the size and weight of the above conventional power-generating device 10 by various design efforts, for example, simplification of the shape and reduction in thickness. However, such size reduction of the power-generating device imposes structural restrictions, and makes it difficult to improve power-generating efficiency by reducing magnetic resistance of the magnetic circuit. In particular, in the case of an electronic wristwatch with a power-generating device, it is necessary to efficiently generate power by a small amount of kinetic energy of an oscillating weight built in a small wristwatch case, and to thereby ensure electric power for driving the wristwatch. Accordingly, improvement of power-generating efficiency is a significantly important problem.
In order to improve power-generating efficiency, it is necessary to reduce magnetic resistance of a magnetic circuit constituted by the rotor 11, the stator yoke 12, and the magnetic core 13 in the power-generating device 10. However, since the principal part of the magnetic circuit has a structure, in which the stator yoke 12 and the magnetic core 13 are joined, as shown in FIG. 19, from the viewpoint of structure and manufacturing cost, leakage magnetic flux cannot be reduced for some reasons, for example, a stepped structure in the joint section. This increases magnetic resistance and decreases effective magnetic flux.
Accordingly, the present invention solves the above problems, and an object of the invention is to achieve a new magnetic circuit structure capable of reducing magnetic resistance, and to provide a power-generating device with improved power-generating efficiency by using the magnetic circuit structure. Another object of the present invention is to achieve a magnetic circuit structure, in particular, suitable for a downsized power-generating device so as to improve power-generating efficiency of power-generating devices built in various electronic devices and to improve the performance of the electronic devices.
In order to overcome the above problems, the present invention provides a magnetic circuit structure including first and second laminated members each composed of a plurality of stacked magnetic materials, and a joint means for holding an end portion of the first laminated member and an end portion of the second laminated member joined to each other, the first and second laminated members joined to each other constituting at least a part of a magnetic circuit, wherein the end portions of the first and second laminated members are provided with opposing concave structures, as viewed from a predetermined direction, so that the opposing concave structures have corresponding shapes, and are joined by the joint means in a state in which the opposing concave structures are mated in a staggered manner, and an end face of a magnetic material of the first laminated member and an end face of a magnetic material of the second laminated member disposed at corresponding positions in the layer-stacking direction are in contact with each other.
According to this invention, since the first laminated member and the second laminated members are joined by the joint means while the opposing concave structures formed in the end portions thereof are mated in a staggered manner, the joint area therebetween is increased. Moreover, since the end faces of the magnetic materials in the end portions of the first laminated member and the second laminated member disposed at corresponding positions in the layer-stacking direction are in contact with each other, magnetic flux is allowed to pass in the planar direction of the laminated members without passing through a stepped portion or a gap. This makes it possible to reliably reduce magnetic resistance in the joint section and to increase effective magnetic flux in the magnetic circuit. Mating of the opposing concave structures mechanically stabilizes the joint state and facilitates assembly operation.
Furthermore, the present invention provides a magnetic circuit structure including first and second laminated members each composed of a plurality of stacked magnetic materials, and a joint means for holding an end portion of the first laminated member and an end portion of the second laminated member joined to each other, the first and second laminated members joined to each other constituting at least a part of a magnetic circuit, wherein the end portions of the first and second laminated members are provided with opposing concave structures, as viewed from a predetermined direction, so that the concave structures have corresponding shapes, and are joined by the joint means in a state in which the opposing concave structures are mated in a staggered manner, and the opposing concave structures are formed to appear semi-cylindrical, as viewed from both the layer-stacking direction and the planar direction of the magnetic materials in the first laminated member and the second laminated member, and are mated in a staggered manner in both the layer-stacking direction and the planar direction.
According to this invention, since the opposing concave structures in the end portions of the laminated members appear semi-cylindrical, as viewed in both the layer-stacking direction and the planar direction orthogonal to each other, it is possible to increase the joint area between the first laminated member and the second laminated member in the joint section, to reduce magnetic resistance, to improve stability of the joint position, and to reduce joint displacement. This can facilitate assembly operation.
In this invention, it is preferable that the end portion of the first laminated member and the end portion of the second laminated portion have contact face portions which extend in the direction of mating thereof and are in contact with each other. According this means, it is possible to further increase the joint area between the first laminated member and the second laminated member, and to further reduce magnetic resistance.
In this invention, it is preferable that the opposing concave structures be formed by the difference in position of end faces of the stacked magnetic materials in the first laminated member and the second laminated member. According to this means, since the opposing concave structures are formed by the difference in position of the end faces of the magnetic materials, it is possible to facilitate production, to ensure joint correspondence between the end faces of the magnetic materials, and to prevent the joint from being displaced in the layer-stacking direction. This further facilitates assembly operation and further reduces magnetic resistance.
In this invention, it is preferable that the joint means joins the first laminated member and the second laminated member by a fastening member that is passed through the end portions of the first laminated member and the second laminated member with the opposing concave structures mated with each other. According to this means, since the laminated members are joined by the fastening member of the joint means in the joint section where the opposing concave structures of the laminated members are mated, there is no need to place the joint means in a section other than the joint section, and the size of the magnetic circuit structure is thereby reduced.
In this invention, it is preferable that at least a portion of the fastening member to be passed through the end portions of the first laminated member and the second laminated member be made of a soft magnetic material. According to this means, since at least a portion of the fastening member to be passed through the joint section is made of a soft magnetic material, it is possible to pass magnetic flux through the portion of the fastening member, and to thereby further reduce magnetic resistance in the joint section. Herein, the fastening member refers to a member for contributing to joining by the joint means, and corresponds to a joint screw and a tube in embodiments which will be described later.
In this invention, it is preferable that the fastening member be composed of a tube inserted in the end portions of the first laminated member and the second laminated member and a joint screw screwed in the tube, and that at least one of the tube and the joint screw be made of a soft magnetic material. According to this means, since both the tube and the joint screw are passed through the joint section, magnetic resistance in the joint section can be reduced by making at least one of the tube and the joint screw of a soft magnetic material. In particular, it is more preferable that both the tube and the joint screw be made of a soft magnetic material.
In this invention, it is preferable that the joint means be provided with a pressing member for pressing the end portions of the first laminated member and the second laminated member, with the opposing concave structures mated, in a direction such that the end portions approach each other. According to this means, the first laminated member and the second laminated member can be pressed against each other in the joint section by being pressed by the pressing member in a direction such that the laminated members approach, the contact (abutting) state of at least a part of the end faces can be made reliable. Even when some end face portions are not in contact with each other, they can be caused to approach, thereby reducing magnetic resistance in the joint section.
In this invention, it is preferable that the pressing member be placed outside the joint section between the first laminated member and the second laminated member. In this case, since the first laminate member and the second laminated member are joined by being pressed toward the joint section from the outside of the joint section by the joint means, there is no need to provide a fastening member or the like in the joint section, and the structure of the joint section can be further simplified.
In this invention, it is preferable that the pressing member be placed so as to be in contact with a side face portion of at least one of the first laminated member and the second laminated member opposite from the end portion and so as to move in a predetermined direction, that at least one of the side face portion and the pressing member be provided with an inclined face which is in contact with the other and is inclined in the predetermined direction, and that the end portions of the first laminated member and the second laminated member be pressed in such a direction as to approach along the inclined face by moving the pressing member in the predetermined direction.
In this invention, it is preferable that the pressing member be a fastening member placed inside the joint section between the first laminated member and the second laminated member so as to fasten the first laminated member and the second laminated member, and that the first laminated member and the second laminated member be pressed in such a direction as to approach (or in the direction of mating of the opposing concave structures in the end portions) by fastening the fastening member. In this case, it is preferable that the fastening member be a joint screw, that the first laminated member and the second laminated member be fastened by rotating the joint screw, and that at least one of the joint screw and the first or second laminated member be provided with a tapered inclined face for pressing the end portions of the laminated members in such a direction as to approach by rotating the joint screw.
In a case in which the joint means in the above means presses the first laminated member and the second laminated member in the joint section, it is preferable that the joint means include a joint screw, and that contact face portions contacting with each other in a direction opposite from the direction of mating of the opposing concave structures (for example, side face portions of concave portions in the opposing concave structures (for example, side faces extending in the mating direction) be pressed in such a direction as to be closely contacted with each other, based on resistance produced in response to the rotation of the joint screw).
The present invention provides a power-generating device having a magnetic circuit structure in any of the above descriptions and a power-generating section, wherein the power-generating section includes a rotatable rotor having a rotor magnetic pole, a stator yoke having a stator magnetic pole opposing the rotor magnetic pole, and a stator having a magnetic core magnetically connected to the stator yoke and an electromagnetic coil wound on the magnetic core, and wherein the magnetic circuit structure is applied to the stator. According to this invention, it is possible to improve power-generating efficiency without increasing the size of the power-generating device. Herein, the first laminated member and the second laminated member correspond to, for example, the stator yoke and the magnetic core.
When there is provided an electronic device equipped with the power-generating device, a longer operation can be expected without a power supply by improving power-generating efficiency. This is particularly effective in a portable electronic device.
It is preferable that an oscillating weight having a biased weight distribution be provided rotatably on the center of rotation and be connected to the rotor. Power can be produced by transmitting the rotation or swing of the oscillating weight to the rotor, and electric power can be taken from the electromagnetic coil.
When an electronic wristwatch is constructed in which a motor is driven by electric power obtained by the power-generating device, it is preferable that the stator structure of the motor adopt the magnetic circuit structure of the present invention.
In this invention, it is preferable that the electronic device include a detection means for detecting the state of rotation of the rotor based on electromotive force generated by the electromagnetic coil, and a rotation control means for magnetically controlling the state of rotation of the rotor via the stator according to a detection value of the detection means. According to this means, since the stator structure of the present invention allows electric power to be efficiently generated by an even small torque, it is possible to reliably operated the rotation control means. It is also possible to improve controllability of the electromagnetic rotation control itself via the stator.
The present invention provides an electronic device including an energy generating means for generating mechanical energy, a gear train for transmitting the mechanical energy, a pointer to be driven by the gear train, the power-generating device to be driven by the gear train, a reference signal generating means for generating a reference signal, and a rotation control means for comparing a rotation signal having a cycle corresponding to the rotation cycle of the rotor in the power-generating device with the reference signal and outputting a rotation control signal for the rotor to the power-generating device according to the result of the comparison so as to exert electromagnetic braking force on the rotor, wherein at least the reference signal generating means and the rotation control means are driven by electromotive force of the power-generating device.
More specifically, there is provided an electronic wristwatch in which rotation energy generated by an oscillating weight is accumulated by a spring or the like, a power-generating device is driven by using the rotation energy, the rotation speed of a rotor is detected based on the output of the power-generating device, an electromagnetic coil wound on a stator is short-circuited according to the rotation speed by a control circuit so as to apply electromagnetic braking force, thereby generating electric power while controlling the rotation rate of the rotor of the power-generating device to be constant, and driving a pointer by the rotation of the rotor.